How to evaluate the quality of woods？

1、Each marketing has its preferences for the value of tree species:
     EX, mahogany is considered a top quality wood in Europe,         
     but only a medium one in China
2、The growth of the core material is an important indicator to judge the quality of wood,
      all long core wood trees, when they  reach a certain growth years,
      their light-colored sapwood will gradually transform into core material,
      the higher proportion of core material, it is deemed the better material
3、In general, the greater the color difference between the core and sapwood,
      that is the better material of the core wood
4、The greater density of wood, its hardness and strength also higher,
      is the better material naturally.
5、High oil，durable aroma，good corrosion resistance
6、The larger diameter of woods is better
7、The woods of the same species grow in different places
     and it's made of different materials and in general,
     the woods grow in the subtropics or the tropics is better than the woods grow in other places;
     the woods grown on high mountains with poor soil is better than that grown in dam
     or hilly areas